Coccidioidomycosis

Risk: Individuals at greatest risk are those exposed to dust, such as farmers, migrant workers, or archeologists, or those who recently traveled in or relocated to endemic areas (areas where the disease is present). Coccidioidomycosis has emerged as an important opportunistic infection (an infection that takes advantage of a weakened immune system). Approximately 25% of HIV-infected individuals living in an endemic area will contract coccidioidomycosis.

Dissemination of the disease is more common in blacks, Filipinos, other Asians, and pregnant women. Individuals with AIDS are more likely to develop pulmonary (lung) coccidioidomycosis as well as the disseminated and cutaneous forms of the disease. Other immunocompromised individuals, such as organ transplant recipients or those taking immunosuppressant medications, are also at higher risk. Dissemination is more common in men than women.

Coccidioidomycosis is typically found in the arid and semiarid regions of the southwestern US (i.e., Arizona, California, and Texas), in addition to parts of Mexico and South America.

Incidence and Prevalence: Acute coccidioidomycosis is not common. An estimated 3% of people who live in an area where the disease is frequently seen will develop coccidioidomycosis (Cooper).

History: Up to 60% of infected individuals are without symptoms (asymptomatic) or have symptoms mild enough to preclude medical attention (Cooper). When symptoms are present, they typically develop within 1 to 4 weeks after exposure. Symptoms of primary infection may include cough, chest pain, shortness of breath, fever, night sweats, fatigue, muscle pain or stiffness, neck or shoulder stiffness, wheezing, sensitivity to light, weight loss, or headache. Some individuals develop joint pain or nodes and lesions on the legs (erythema nodosum). Individuals may have a history of residence or travel in endemic areas.

Physical exam: Individuals may present with a fine rash, fever, and migratory joint pain upon physical examination. There may also be evidence of pneumonia, including a cough with increased sputum production. Abnormal lung sounds indicate inflammation of the membrane surrounding the lung (pleurisy). Evidence of disseminated infection includes lesions; bone infection (particularly in the vertebrae and long bones); joint infection or pain, including arthritis; ankle, feet, and leg swelling; enlarged lymph nodes; and contained areas of infection (abscesses). Altered mental status, headache, and vomiting are often present in individuals with meningitis.

Tests: Coccidioides immitis can be identified in culture or microscopic examination of pus, urine, cerebrospinal fluid (CSF), or tissue. A sputum smear may reveal the presence of fungal microorganisms. A coccidioidin skin test is positive in more than 95% of individuals with primary coccidioidomycosis. A negative test, however, does not rule out the infection. It may take several days or weeks for an individual to present with a positive reaction. In an individual with a known coccidioidomycosis infection, a negative skin test indicates that the infection may be disseminated. A coccidioides complement fixation test may reveal the presence of antibodies to the fungus coccidioidomycosis by a particular serologic technique. A complete blood count (CBC) to measure the number of eosinophils (a type of white blood cells) may be performed. Other blood (serology) tests are useful both for diagnosis and prognosis, although these tests may be negative in immunocompromised individuals. Tests may include immunodiffusion test (counterimmunoelectrophoresis [CIE]), tube precipitin test, and antibody titers. Lumbar puncture may be done to rule out meningitis. X-ray studies, MRI, or CT can indicate the spread of the disease.